1981 VW Gas Pickup to Diesel Conversion Project

chemglider

Member
Joined
Jun 18, 2009
Location
Elk Grove, Ca
TDI
1981 Pickup
I am a high school science teacher and a backyard mechanic with decent mechanical skills. As a summer project, I recently purchased a 1981 vw gas pickup that was in the process of being converted to a turbo diesel. I purchased the 1977-1984 Bentley diesel service manual. I am not getting fuel to the Injection Pump. I used a primer bulb to pump the fuel to the filter and past then clamp the hose to maintain pressure. (I placed a piece of clear hose in the fuel line to let me know if the fuel is in the line). When I hook the fuel line to the IP, the fuel seems to run back to the tank. When I crank the engine, the IP does not draw the fuel. The injectors have been disconnected. Any suggestions are truly appreciated.
 

Diesel_Aggie

Veteran Member
Joined
Nov 3, 2005
Location
College Station, Texas
TDI
1996 B4, 1996 B4V
Have you tried unhooking the fuels lines at various places and blowing compressed air thru the lines? I had a blockage on my '82 Caddy earlier this year that what blocking 95% of the fuel flow. A good blast of air cleared it right out.
 

coalminer16

Top Post Dawg
Joined
Dec 11, 2008
Location
Central Wisconsin
TDI
Golf 2004
Leave the primer bulb in the line. I have it on both of my 81 rabbits and my brother does to with no issues. Makes changing the fuel filter easier. Unless the pump is completely full of fuel the pump will take a LONG time to prime itself. As in you will need to get a battery charger possibly and let your starter cool off. Put the primer bulb in the line, crack the bleeder on the fuel filter housing til only fuel comes out. Then crack the return fuel banjo bolt untill only fuel comes out. Then you are ready to crack the fuel lines to the injectors. Once fuel comes out all four injector lines then tighten and start. Has worked for me each time with less wear on the starter and injection pump.
 

PDJetta

Top Post Dawg
Joined
Nov 6, 2003
Location
Northern Virginia
TDI
'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
If the mainshaft seal is not sealing, the pump will not draw fuel. You can replace this seal (its tight as all in the IP pump, a doable job, but not fun) and hope for the best. If the old seal was dry rotted, this takes care of the problem. If the mainshaft bushing is worn, the fix is only temporary. See if there is excess play on the IP shaft in the direction the timing belt pulls the sprocket. This is a problem when the timing belt is over tensioned (the IDI VW diesels do not have automatic tensioners, you have to set and lock the belt tension). It is easy to overtighten this belt when changing it.

Try this: Remove the fuel line banjo fitting from the top of the IP and pour clean diesel into the pump to fill the cavity. Install the fitting and fuel line and see if it will start and run. If it sits over night and won't start the next day, I would suspect the IP mainshaft seal. Sometimes they leak fuel, and sometimes just air will leak into the pump. If it leaks fuel, this leak is very hard to see because it is behind the timing belt cover and injection pump pulley.

--Nate
 
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